Film drying method and apparatus



June 2, 1942. H. P. ELLIS mm mum u'mmon ma Agrmuus 2 Sheets-Sheet 1 Fild July 19, 1941 H. P. ELLIS FILM DRYING METHOD AND APPARATUS Filed July 19, 1941 INVENTOR.

June 2, 1942.

Patented June 2, 1942 UNITED STATES PATENT OFFICE.

FILM DRYING METHOD AND APPARATUS Hamilton P. Ellis, Fort Sheridan, Ill. Application July 19, 1941, Serial No. 403,200

8 Claims.

This invention relates to improvements in filmdrying machines and methods ofdrying films while wound on film reels or spools of the kind commonly used in developing tanks.

The principal object of the invention is to provide a novel form of machine and method for drying the film rapidly and safely while wound on such reel or spool, including means for automatically indicating to the operator whenthe film is completely dry and ready for removal.

In carrying out my invention I provide a cabinet having a cylindrical receptacle open at the top for receiving the film reel with the film wound thereon. Means for supplying heated air under pressure is connectedto the lower end of the receptacle so as to force air upwardly through the air vents in the opposite ends of the film reel in order to pass between the adjacent surfaces of the film. The air current is capable of manual control so that when the film and reel are inially inserted in the receptacle in wet condition the amount of air is adjustable so that it is not quite sufficient to lift the reel and its film on account of the weight of the water adhering to the film surfaces." An auxiliary weighting device is also employed in connection with the reel corresponding substantially in weight to the amount of water that would normally adhere to a film of predetermined length. Thearrangement is such that the film is ready for removal.

The air current is preferably supplied by a blower having an intake disposed within the cabinet and protected by suitable filtering means so as to avoid the depositing of dirt, lint or the like on the film surfaces while drying. I also provide selective means for controlling and maintaining the air current at the proper drying temperature so as to avoid the danger of overheating or scorching the film in the hands of inexperienced operators.

Theinvention may best be understood by reference to the accompanying drawings, in which Fig. 1 is a perspective view of a cabinet type film-drying apparatus constructed in accordance with my invention. i

Fig. 2 is a detail plan view of a film reel of the type especially adapted for use with the apparatus shown in Fig. 1.

Fig. 3- is an enlarged vertical section taken transversely of the cabinet illustrated in Fig. l, and showing the film reel in drying position therein. 1

Fig. 4 is a plan view of the cabinet, with parts broken away to show interior details, and with the film reel removed.

Fig. 5 is a vertical section taken longitudinally of the cabinet.

Fig. 6 is a wiring diagram showing the several electric control connections used with theappa ratus. I

Fig. '7 is a detail view of a plurality of stoppers of various weights which may be used with films of various sizes.

Referring now to details of the embodiment of the invention illustrated in the drawings, the apparatus is for convenience enclosed-in a cabinet l0, and comprises as its main elements a cylindrical receptacle ll mounted at the top of the cabinet and opening upwardly, anda blower or fan 12 mounted in the cabinet and discharging into the botttom of said receptacle through a duct I3. I

The receptacle II is of proper size to receive a film reel H which herein is of the well-known type commonly used with a developing tank (not shown), and. consisting of a hollow hub to hav,-

ing opposed parallel end discs l6, IS with spiral grooves formedin their inside faces so as to receive the edges of a film 9 therein when the lat ter is wound onthe reel in the usual manner, so as to hold the adjacent surfaces of the film in spaced relation. A series of slots or openings l1, I! are formedas usual in the end discs, primarily designed to permit free access of the developing solution tothe filmsuriaces during the developing operation. It will be understood that in the usual manipulation of such reels, the film is developed and rinsed while wound on the reel,

but the film is usually unwound and hung endwise in air for drying. As will presently appear, I make use of the reel in a novel manner for drying the film without unwinding it fromthe reel. 0

The blower l2 includes rotor blades 20 propelled by an electric motor 2| as usual. An intake duct 22 leads to the blower from the exterior of the cabinet, through a suitable air filter 23, herein consisting of a mesh screen 26 across the end of said intake duct, a perforated plate 24 spaced from said screen andforming part of the side wall of the cabinet, a casing 25connecting the end of the said intake duct with the plate 24, and with suitable filtering material 2! such as wool in said casing.

An electric heating element 28 of any suitable form, herein consisting of coiled resistance wires, is disposed in the air discharge duct l3 leading to the receptacle ll.

Means for controlling the volume of air supplied to the receptacle is also provided, herein consisting of a vane or plate 30 mounted on a horizontal shaft 3| having suitable bearings 3|, 3| in the cabinet, and extending through the front wall of the cabinet, with a knob 32 and pointer 33 fixed on its outer end. The vane is mounted to swing into and out of a slot 34 in the air intake duct 22 so that the volume of air supplied to the blower and finally entering the A receptacle II can be controlled by manipulation of the knob 32 on the front of the cabinet.

The operation of the apparatus may now be described as follows:

After the film is developed and rinsed on its reel I 4 in the usual manner, the reel and film are transferred directly to the receptacle, as indicated in Figs. 3 and 5, with the bottom flange of the reel resting by its own weight on the bottom of the receptacle.

In connection with the apparatus, I provide one or more weighted members, herein in the form of stoppers or corks 36, 36 In practice, one of these stoppers is inserted in the open upper end of the hollow hub I5 of the reel. A plurality of stoppers of different weights are preferably provided as a part of the apparatus for selective use, depending upon the size or length of film to be dried in each instance.

With the proper stopper inserted in the reel, the blower is turned on so that the air current is forced upwardly through the slots H, H in the reel and between the adjacent film surfaces. This air current, of course, has a tendency to lift the entire reel, but by means of the control knob 32 the volume of air is initially adjusted at the start of the drying operation so that the combined weight of the reel which includes the film 22 and the stopper 3B, is approximately counterbalanced by the air blast, and rests on the bottom of the receptacle just short of floating on the air current, It will be understood, of course, that the water on the film assists in weighting down the reel. As drying proceeds, the loss of water from the film permits the reel to rise gradually and float on the air current in the receptacle until said reel reaches a predetermined level at which the film is entirely dry. 1

cally, causing actuation of a signal device, such as a bell 43.

-It will now be understood that the stopper member 36 serves the double purpose of adding sufficient weight to the film reel (as determined by initial experiment) to insure the proper floating action of the reel for a given size or length of film to be carried thereby, and also to close the central hollow opening usually formed through the hub l5 of commerciak forms of film reels so that most of the drying air will be forced through the main body of film reel. It will be understood further, however, that the film reel itself may be especially designed and weighted so At this predetermined level, a suitable stop,

herein consisting of an electric switch member 38, is mounted adjacent the rim of the receptacle (see Figs. 4 and 5). In the preferred form shown, said contact member comprises two coni tact; springs 39, 40 suitable insulated from each other on an upright shaft 4| mounted on the top wall of the cabinet adjacent the rim of the receptacle. The free ends of the contact springs 33, 40 can thus be swung laterally by means of a turning knob 42 on shaft 4|, into and out of registering position over the said receptacle, to facilitate insertion or removal of the reel.

The stop signal arrangement just described is such that when the film is thoroughly dried, the reel I4 is lifted or floated to the predetermined level to engage switch 38 and close it automatithat a stopper 36 may be dispensed with.

The electrical connections employed with the apparatus above described is illustrated in the wiring diagram, Fig. 6. The main supply conductors 45, 46 are connected to a source of power as usual. The signal bell 43 with its contact switch member 38 are connected across said conductors. Likewise, the blower motor 2|, with its control switch 21* are connected across said main conductors. For convenience the switch Zi is mounted on the front wall of the cabinet, as shown in Fig. 1,

As a preferred arrangement for controlling th air heating element28, I provide a switch 28 and a fixed resistance 41 arranged to be connected in series therewith through a double-throw switch 48 so that in one position of the latter switch the heating element will deliver air to the receptacle only at a moderate temperature suflicient to dry the film without danger of damaging the latter due to overheating. A signal light 49 may be connected in parallel with the fixed resistance so as to indicate when the moderate, film-drying current is turned on. In the other position of switch 48, the fixed resistance 41 is cut out, so

that the air temperature will be somewhat higher if desired for other purposes. With the arrangement illustrated, however, the operator will know that the apparatus should not be used for dryingfilm unless the signal lamp 49 is lighted.

It will be understood, of course, that various modifications in the control circuits may readily be employed. For instance, instead of the signal light 49, a signal light can be used in parallel with the heating circuit when the fixed resistance 41 is cut out, to serve as a warning to the operator that the air blast is too hot for film drying. These, and other modifications in air blast and electric control devices may be employed without departing from the spirit and .scope of my invention as defined in the appended claims.

I claim as my invention:

.1. The method of drying film on a vented film holder of the type used in developing tanks, which consists in placing the film holder with a film mounted thereon into a receptacle, forcing a blast of drying air upwardly through said receptacle, with the volume of said blast and the combined weight of the reel initially adjusted so that the holder and film may be approximately counterbalanced by said air blast while in wet condition, but will be freely floated on said air blast to a predetermined higher level when the film is dry.

2. In a film-drying apparatus, a vented holder adapted to hold a film, a receptacle for said holder, air blast means connected with the bottom of said receptacle in a direction tending to float said holder on a column of air produced by said air blast means, and control means for adjusting the volume of air from said air blast holder may be approximately counterbalanced -wet, and be floated by. said air blast means to a predetermined. higher ,level in said receptacle when the film has become dried.

3. In a film-drying apparatus, a vented film means, and control means for initially adjusting the volume of air from saidair blast means so that the combined weight of said film holder may The approximately counterbalanced by said air a blast when the film on said holder is wet, and be floated to apredetermined higher level in said receptacle when the film has become dried by said air blast, and signal means including a control member arranged to be actuated by said film holder for automatically eil'ecting operation of said signal means 'at said predetermined level.

: *4; In 'a film-drying apparatus, a vented holder.

a receptacle for said holder, air blast means connected with the-bottom of said receptacle in a direction tending to float said holder on a col- 6. In a film drying apparatus, a vented film 50 y umn oi. air produced bysaid air blast means, auxiliary weighting means detachably connectible to said'film holder, and control means for adjusting the'volume of air from said air blast means so that the combined weight of said film holder may be substantially counterbalanced by a answer means sothat the combinedweigbt of said film by said air blast when the film on said holder is V holder, a cabinet, ,a receptacle for said holder mounted on the-'top of said cabinet, air blast means within'said cabinet connected with the bottom of said receptacle, an air inlet for said air blast means opening through the wall oi said cabinet and having air filtering means therein, and control means for adjusting the volume oi air from said air blast means so that the combined weight carried by said film holder may be approximately counterbalanced when the film on said holder'is wet; and said reelmay be floated, to a predetermined higher level in said receptacle by said-air blast when the filmhas become dried. 1

'7, In a-film-drying apparatus, a vented holder adapted to hold a film, a receptacle for said holder, air blast means connected with the bottom of said receptacle in.a direction tending to float said holder on a column of air produced by said air blast means, and control means for adjusting the volume of air from said air blast means so that the combined weight of said film holder may 7 be approximately counterbalanced vby said air blast when the film on said holder is wet, and

be fioated by said air blast means to a predeterfilm has become dried, and an electric heating element for said air blast means including a fixed mined higher-level in said receptacle when the resistancein series therewith to guard against said air blast when the film'on said holder is wet,

in said receptacle when the film has become dried by said air blast. ,1

i and -bei-fioated to a predetermined higher level 5. Ida film-drying apparatus and in combination with a vented film reel having a hollow spool.

connected with the bottomof said receptacle,

-- auxiliary weightingmeans for said reel adapted to be inserted in the open end of said hollow spool, control means for adjusting the volume oi from said air blast means so that the combined weight of said reel may be substantially counterbalanced by said air blast when the film on said reel is 'wet and'befioated to a predetermined higher level in said receptacle when the film has become dried by said air blast 'means.

overheating oi. said'air blast.

8. In afilm-drying apparatus, a vented holder *adapted to hold a'film, a receptacle for said holder, air blast means connected with the bottom 01' said receptacle in a direction tending to fioat said holder on a column of air produced by said air blast means, and control means ior adjustingthe volume of air from said air-blast vmeans so that the combined weight oi said film a receptacle ior'said film reel, air blast means.-

holder may be approximately counterbalanced against overheating of said air blast, and visual signal means associated with said heating circuit to indicate when the apparatus is safe for film I Hamilton P. ELLIS.

by said air blast when the film onsaid holder is wet, and be floated by said air blast means to a predetermined higher level in said receptacle, 

